* cmd/swarm: fix manifest subcommands and add tests

* cmd/swarm: manifest update: update default entry for non-encrypted uploads

* swarm/api: upload defaultpath file only once

* swarm/api/client: improve UploadDirectory default path handling

* cmd/swarm: support absolute and relative default path values

* cmd/swarm: fix a typo in test

* cmd/swarm: check encrypted uploads in manifest update tests